Picture please? I'm not an expert on how TAE electrophoresis can go wrong, but I have some experience and a gel image would help.

Hello Bong. I think you should review your protocol in detail. Did you confirm that you actually had positive samples at the end of your upstream analysis?  What was the concentration of the solution that you used? Did you employ the use of an appropriate dye in the gel analysis? e.t.c.

Hello Mr. Evans, there was no way to get any picture at all because nothing was on the gel at the end of electrophoresis. Sorry for that.

Mr. Olarinmoye, thanks for your answer. You may be right. Of course, I had positive results previously, and the concentration of TAE used is 1X. I prepared another stock last friday, and it is with this new solution that I noticed this strange behavior. I hope that I mishandle while preparing TAE, I used PBS 1X instead of distilled water.

Dear Mukendi,

Thanks for your answer. You have just quoted some important factors to be considered but I can ensure that all the conditions set were correct (time, volt, etc.). That's why I suspected the buffer I used. Thanks

Make sure you connect the electrophoresis apparatus correctly with the power supply (red with red and blue or black with blue or black) because sometimes mix can happen and if any mix happen your DNA sample will run in the opposed direction and pass out and you can not see any things in the gel even the ladder. 

Thanks a million dear Yousif

Hey Bongo,

Check whether you added a dye before loading your amplicons onto the gel?  if not they might not settle in the wells and wipe out

Check whether the sense of the power supply and the electrophoresis machine is correct before you plug it. If wrongly done, the amplicons might migrate in the opposite directions...

I think you just have to redo it. And this time be cautious.

Thanks dear Dr. Hounmanou